Computing systems obtain a high degree of functionality by executing software programs. Programs consist of computer-executable instructions that are kept in some persistent form, such as on a harddrive, a compact disk, a thumbdrive, flash memory, or the like. During execution, such computer-executable instructions may often be loaded in random access memory, and executed by one or more processors of the computing system, causing the computing system to perform tasks.
In object-oriented programming, these computer-executable instructions are organized into objects that interact through function calls, and that may have one or more properties. Managed code is code that runs in a managed environment that provides type safety, but may also provide memory management and exception handling. In managed code, objects have unbounded lifetimes, no restriction on storage, and methods of access restriction involve indirection or extra resources.
Systems level programming is based upon tight and efficient management of access to and lifetime of resources (such as objects) throughout the system. One common way to provide this tight management is to use an Application Program Interface (API) to manage the lifetime and access of the resource.